There is provided a content automation system and a method for use by the content automation system for issuing a content management message for use in a program stream. In one implementation, such a content automation system comprises a processor and a memory, and a stream messaging module residing in the memory. The stream messaging module is configured to issue the content management message by embedding a command sequence as metadata in a container data structure, and inserting the container data structure into the program stream. The command sequence authorizes a replacement of program stream content.